1. Technical Field
The present invention relates to a solid state imaging device.
2. Related Art
A back side incident type solid state imaging device is disclosed in Japanese Laid-open patent publication No. 2002-33469. The solid state imaging device includes a semiconductor substrate and a light receiving portion formed on a surface layer thereof. Light from an object to be imaged incident on the back side (on the side opposite to the side where the light receiving portion is provided) of the semiconductor substrate is photoelectric-converted inside the semiconductor substrate. Then, the light receiving portion receives electric charge generated by the photoelectric conversion, and therefore imaging of the object to be imaged is performed.
There can be included Japanese Laid-open patent publication Nos. H3-296280, H2-285633, 2000-77641, and 2000-252452, respectively other than the above mentioned patent document, as related art documents related to the present invention. In Japanese Laid-open patent publication Nos. H3-296280 and H2-285683, there is disclosed a back side incident type of solid state imaging device which images an object to be imaged on the basis of a principle different from the Japanese Laid-open patent publication Nos. 2002-33469. Furthermore, in Japanese Laid-open patent publication Nos. 2000-77641, and 2000-252452, there is disclosed a surface incident type of solid state imaging device.
However, in the solid state imaging device described in the Japanese Laid-open patent publication No. 2002-33469, there is a room for improvement in sensitivity. As a part of the reason for lowering sensitivity of such solid state imaging device, it may be included that a part of signal electric charge generated inside the semiconductor substrate disappears by recombination.